When an electronic component, such as a relay, in a tool breaks down, there is a risk that too much electrical power is transferred to the other components in the tool. Many electrical components can withstand receiving too much power, and electrical systems are often designed to turn off the power in cases like this.
However, when working downhole, communication to and from the tool as well as communication within the tool can be difficult. Higher security is especially important in tools handling drilling units, explosives or cement to ensure that they do not perform uncontrolled operations, such as explosives not being detonated, drilling tools drilling in an uncontrolled direction or cement being ejected unintentionally, thereby closing the well.